Magnetic read/write heads, such as those used in hard disk drives, include a magnetic transducer with a write element and a read element disposed on a substrate. The write element is an inductive transducer, which includes electrically conductive coil windings that are encircled by a magnetic core. The magnetic core includes a first and second pole tips with a non-magnetic gap disposed between the tips. When electrical current flows through the coil a magnetic field is induced across the non-magnetic gap at the pole tips to write on the magnetic media, i.e., the hard disk, which is near the pole tips.
The read element is typically formed between the write element and the substrate and typically includes first and second shield layers with a magnetoresistive (MR) sensor formed therebetween. Magnetic flux from the surface of the magnetic media causes the rotation of a magnetization vector in the MR sensor, which causes a change in resistivity. Thus, the presence of magnetic flux at the surface of the magnetic media may be detected by measuring the change in resistivity of the MR sensor.
The read/write elements are located at the trailing end of the substrate along the air bearing surface. In operation, the head flies above the spinning magnetic disk so that the read/write elements are positioned in close proximity to the magnetic recording media. Ideally, the read/write elements are close enough to the magnetic media to produce a large data density, however, the distance should be great enough that contact between the read/write elements and the magnetic media does not occur.
Because the read/write elements are fabricated from materials different from that of the substrate, the read/write elements and the substrate typically have differing coefficients of thermal expansion (CTE). Generally, the read/write elements include metallic layers causing the read/write elements to have a greater CTE than the substrate. During operation, as the read/write head flies above the spinning magnetic media, the read/write head is subjected to increased temperatures. The increased temperatures and the greater CTE of the read/write elements causes the read/write elements to protrude closer to the magnetic media than the substrate, which is known as thermal pole tip protrusion (T-PTR). Thus, T-PTR requires an increase in the fly height of the read/write head in order to avoid contact between the read/write elements and the magnetic media during high operating temperatures.
Accordingly, it is desirable to reduce the amount of T-PTR in a read/write head so as to reduce variation in the distance between the read/write elements and the magnetic media during operation, which permits a decrease in the required fly height of the head.